How to read UFC odds
Updated 2026-10-01
Every UFC betting line is a probability in disguise. Once you can turn odds into a percentage, you can compare the bookmaker with your own read of the fight – or with a model – and see straight away whether a bet is worth anything.
American odds: the minus and the plus
American (moneyline) odds are the format most UFC coverage uses. The favourite has a minus sign, the underdog a plus sign.
A minus number is how much you stake to win 100. At -250 you risk 250 to win 100, so a winning bet returns 350 in total. A plus number is how much you win on a 100 stake. At +180 a 100 bet wins 180 and returns 280.
The bigger the minus number, the heavier the favourite. The bigger the plus number, the longer the underdog.
Decimal odds
Decimal odds, standard in Europe and Australia, show the total return per unit staked, stake included. Odds of 1.40 return 1.40 for every 1 staked; odds of 2.80 return 2.80.
To convert: for a minus line, decimal = 1 + 100 / |odds| (so -250 becomes 1.40). For a plus line, decimal = 1 + odds / 100 (so +180 becomes 2.80).
Implied probability
Implied probability is the win chance the price assumes. With decimal odds it is simply 1 divided by the odds: 1 / 1.40 = 71.4% and 1 / 2.80 = 35.7%.
From American odds: for a minus line, |odds| / (|odds| + 100), so -250 is 250 / 350 = 71.4%. For a plus line, 100 / (odds + 100), so +180 is 100 / 280 = 35.7%.
The bookmaker margin (the vig)
Add the two implied probabilities from the example together and you get 107.1%, not 100%. The extra 7.1% is the bookmaker margin, also called the vig or overround. It is how the bookmaker gets paid whoever wins.
To get the market's real opinion, divide each implied probability by the total: 71.4 / 107.1 = 66.7% and 35.7 / 107.1 = 33.3%. These "no-vig" numbers are what FIGHT//AI shows as the market probability on every fight page.
Margins differ between bookmakers and between markets. Main-event moneylines are usually tight; method and round props often carry much bigger margins, which makes them harder to beat.
Why line shopping matters
Different bookmakers post different prices for the same fight. Taking 2.10 instead of 1.95 on the same fighter is a 7.7% bigger return every time that fighter wins, and over a season that difference is often bigger than the edge of any prediction.
Fight pages on FIGHT//AI show an average line across bookmakers. When you bet, compare a few books and take the best price.
Putting it to work
Odds alone do not tell you whether to bet. They tell you what you need to believe. If a fighter is priced at 2.80 (35.7%) and you think their real chance is 45%, the bet has positive expected value. If you think it is 30%, it does not, however good the fighter looks.
That comparison – your probability against the price – is the whole game. The next article, on expected value, shows how to do it properly.